Noninterest Income - Investment Banking Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Investment banking revenue:
Underwriting fees	$ 31,290	$ 35,772
Advisory fees	15,487	12,273
Private placements and other	90	1,750
Total investment banking revenue	$ 46,867	$ 49,795

Includes (1) underwriting revenue (the spread between the resale price received and the cost of the securities and related expenses) generated through the purchasing, distributing and reselling of new issues of securities (alternatively, could be a secondary offering of a large block of previously issued securities); and (2) fees earned for mergers, acquisitions, divestitures, restructurings, and other types of financial advisory services.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(b),(d))
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration